What are the standard equipment/weapon builds for a heavy (both offensive and defensive), when combined with a Medic?
Note: I don't play Heavy a lot, so this is mainly observation from watching others play Heavy.
Heavy builds tend to vary depending on the types of enemies you're facing.
The standard "medic buddy" offensive build is this:
The standard "medic buddy" defensive build is this:
Note: If you're having problems with lots of Scouts, swap the Minigun out for the Natascha.
Note 2: The new weapons aren't listed here simply because they're new and some people are still getting them... and thus they haven't been tested that much.
A new Offensive build may be:
Defensive build is likely better unchanged from standard.
Now, as for the items above:
The Sandvich is a controversial choice. Generally, you have it so you can throw it to your Medic if his Health is low. However, you lose your Shotgun, and the Shotgun is both a good backup weapon, and a good weapon to have equipped in case someone surprises you on the way to the battle front.
Largely, the melee weapon isn't used that often by the Heavy. Therefore, choose it based on its effects.
The Gloves of Running Urgently is a good choice for offensive if the team has no teleporters, because you can get to the front lines faster with it. However, its mini-crit effect leaves makes you much easier to kill if ambushed on your way there.
The Fists of Steel is useful if your Medic has died and you need to escape due to the reduced damage taken from ranged weapons.
Of course, there are other options.
In general, the Brass Beast makes you move too slowly when shooting it and the spinup time is too long. Its drawbacks are too great and a Heavy vs Heavy battle will likely go to the other Heavy if they manage to surprise you. Also, the weaker classes already die quickly enough to the standard Minigun.
I've seen at least one person who mains Heavy switch out his Shotgun for the The Family Business. It does slightly lower damage, but you have 8 shots before reloading rather than 6 with the regular Shotgun.
The Tomislav is a new minigun with no spinning sound (although it does make a noise when you raise or lower it) and it spins up faster. This can replace the need for the Shotgun in your build, as your spinup time is decreased by 40%.
Typically the only two items you will use in the second slot will be shotgun or sandvich. You will want to use the Sandvich if you are separated from your medic, or if you need to help your medic heal up by dropping it (right click to drop it). If you need more mobile damage use a shotgun as you don't have to spin-up to use it.
In the melee slot the most useful items will be the Warrior's Spirit or the Gloves of Running Urgently (GRU). You would want to use the Warrior's Spirit when you are trying to maximize your damage, and use the GRU when you need to get to locations faster (say cp mode).
The primary slot is where most of the business happens, and it can affect what you want in your melee slot.
Typically the Minigun (Sasha) is a good all-around gun. It doesn't have the negatives (such as slowing you down) that some of the other weapons have, but it doesn't have the benefits either. It's a good weapon to use when you want higher damage but want to maintain at least some mobility.
Typically the Natascha is great when you are trying to suppress an area against very mobile targets. It's limited in that it doesn't do as massive damage as other weapons do, so it can only go so far.
Typically the Brass Beast is hard to play because the reduced mobility makes you quite vulnerable, but sometimes you need that extra punch. Use with caution.
I have found the Tomislav to be an incredibly mobile weapon. It spins up and down much faster than any other primary weapon, and this makes surprise attacks much more effective. When combined with either the GRU or Warrior's Spirit you are a force to contend with.
Hope this helps